I had a samsung omnia which also had a usb cover, it felt very brittle (although less so than the pre) after a year it was still on there and I was opening it several times a day. So I figure ill give the pre`s a chance too

1) I've had my Pre since launch day (no exchanges, no issues) and removed the usb cover the next day. There are 4 other Pres in my immediate family and all usb covers have been removed since September. We all constantly connect our Pre usb to various labtops to move music and pictures.

2) Never tried to put the usb cover back on. No case or screen cracking.

I've been reading horror stories of build issues and multiple returns. So far with 5 Pres in the family, we've had no returns for build quality. We've been blessed & dont take it for granted.

1] Is there any adverse effect of having the port exposed 24/7 ? If not, why have a cover to begin with...

2] Many stateside Pre owners reported issues of the case or screen CRACKING when popping the USB cover back in ==> want to avoid!

Response to 1]
If you keep your phone in your pocket, dust will slowly but surely collect in the space. If you plug your USB into it daily then your connections stay pretty clean but you shove the days dust and dirt further into the plug and into the device. You may or may not get affected by this but it certainly isn't good for cooling or any mechanical parts (the slider). If you don't use the port, it will fill with dust and become hard to clean out or you'll just end up shoving the dust in a large glob into your case/port when you end up using the port. The dust may even be thick enough to prevent proper connections effectively disabling the port.

Short term you wont see anything happening. Long term you run the risk of overheating components, mucking up the slider, or disabling the USB port.

Keep in mind this is a process taking months and years and depends on the environment of your pocket and the case you use. Using a proper case, you can hide the port effectively enough that you would never see a problem in the devices lifetime.

Response to 2]
I can't even imagine how you could do this unless the screen was already defective. It's probably related to the other screen cracking issues and applying side pressure (pushing the cover on) pushes a screen flaw to failure. In which case, you'd want to apply this pressure when it was still under warranty.